Air bag deployment systems for automotive vehicles generally employ an inflator to inflate and deploy the air bag. Conventional inflators typically include a pyrotechnic material. When burned, the pyrotechnic material produces a nontoxic gas which is used to inflate the air bag. Some inflators utilize a pressurized gas to inflate the air bag.
Inflators are activated by initiators. Initiators are also referred to as squibs or ignitors. Initiators are devices which, when activated, ignite the inflator's pyrotechnic material so as to produce a gas. In the case of a pressure inflator, when its initiator is activated, a projectile is propelled through a membrane to release the inflator's pressurized gas.
In today's air bag systems, inflator firing is confirmed by observing the condition of the inflator control circuitry connected to the squib of the inflator. Previous methods for indirectly determining if an inflator is activated include determining if a control switch of the control circuitry is closed, measuring the current provided to the squib, or measuring the resistivity of the squib. These indirect methods assume that a dud or misfire did not occur in the squib and do not directly determine if an inflator failure occurred.
Inadvertent firing of the inflator is a potential problem in some air bag systems which can result in an air bag being unintentionally deployed. This can be caused by electrostatic discharge energy or Radio Frequency (RF) signals such as signals from a radar or high powered radio transmitters. This type of energy can be transmitted to the squib and inadvertently heat the pyrotechnic material of the squib to its flame temperature.
Accordingly, it would be advantageous to have an air bag deployment system and method that prevents inadvertent air bag deployment. It would be of further advantage to have a system and method for directly detecting inflator failure and that activates alternate safety devices in the event of inflator failure.